In a scenario of MIMO (Multiple-Input and Multiple-Output, multiple-input and multiple-output), detecting demodulation by using ML (Maximal Likelihood, maximal likelihood) may enable a system to have optimal bit error rate performance, thereby gaining wide application. The complexity of the ML algorithm usually increases exponentially along with the total number of streams of the MIMO and a modulation order, so in the existing wireless communication system standard protocol, commonly a low-order modulation manner is adopted. Because once higher-order modulation is adopted, the complexity of detecting the demodulation by using the ML is almost unacceptable.
However, in another aspect, as the cellular is becoming smaller, and the interference management technology develops, the higher-order modulation manner may be increasingly applied in a cellular network or other wireless networks. Therefore, the problem of the complexity of detecting the demodulation by using the ML algorithm may become more prominent.